Colorado River Basin Is Drying Up in 'Potentially Catastrophic' Impact of Climate Change

Potential future drops in the volume of water flowing in the Colorado River due to climate change could have catastrophic consequences, an expert has warned Newsweek.

Brad Udall, senior water and climate research scientist at Colorado State University, made the comments regarding a paper published in the journal Science.

The study highlighted that climate change appears to have led to the loss of snow in the Colorado River Basin, which in turn is thought to have caused the body of water to absorb more solar energy, meaning more water evaporates.

The Colorado River has been suffering a drought due to higher temperatures since 2000, and researchers warn if trends of its flow dwindling continue there is a risk of severe water shortages for the around 40 million people and 16 million jobs it supports.

The team set out to answer how vulnerable the river is to rising temperatures and a lack of rain. They estimated that as snow and ice melt, causing what is known as the albedo (how much light hits a surface and is reflected without being absorbed) to be lost, the river's flow will diminish by 9.5 percent for each 1 degree celsius of warming. This drying process will likely outrun the increase in rain which global warming is expected to usher in, the scientists fear.

The team forecast the river's future state by creating a computer model based on existing data with factors including the monthly water-balance, average levels of rain and temperature in the area, as well as water contained in the nearby snowpack. They also worked out the balance between the energy the area receives from the Sun versus the albedo of snowy areas.

Udall, who has previously worked with the authors of the paper but wasn't involved in this project, told Newsweek: "The study strongly supports recently published research that says half of the flow loss in the Colorado River during the ongoing drought since 2000 has been due to higher temperatures."

He said he was surprised at how "exceedingly" sensitive the river's flow was to temperature, and said this "should be of great concern to everyone who depends on the river."

The results "strongly suggest that future Colorado River flows will trend strongly downward as temperatures warm in the 21st century, potentially catastrophically," he said, adding: "these findings apply to almost every area that is dependent on snowpack, which is basically the entire West."

"In the Colorado River Basin, when you touch water, you touch everything—our economy, our culture, our environment. Flow losses will impact U.S. agriculture, all aspects of our economy including world-class Rocky Mountain tourism and our way of life," he said.

Udall added there is a strong link between the loss of snowpack and "devastating fire seasons" which, evidenced by recent blazes in California and Australia, have the potential to "destroy communities."

"More broadly, these results tell us that we need to reduce greenhouse gas emissions as soon as we possibly can," he said. "We've wasted nearly 30 years bickering over the science. The science is crystal clear—we must reduce greenhouse gas emissions immediately. We now have the technologies, the policies and favorable economics to accomplish greenhouse gas reductions. What we lack is the will."

Greg McCabe is a research scientist with the U.S. Geological Survey in Colorado and supervisor for the authors, who did not work on the paper. He told Newsweek the study was limited because it is difficult to completely and accurately model hydrologic processes—those which relate to the movement, distribution and management of water—as there are "always uncertainties associated with model simulations."

"However, this analysis has provided a more physically-based estimate of the magnitude of the effects of warming on Upper Colorado River flow than has been provide by previous studies," he said.

Asked how the loss of river flow affects the local community and the U.S. more widely, he said: "The Colorado River basin extends across parts of seven states (Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming) and is one of the most important water resources in the western U.S. and Mexico.

"The Upper Colorado River Basin (UCRB)—that portion of the Colorado River basin upstream of the streamgage at Lees Ferry—accounts for about 90 percent of the streamflow of the entire Colorado River Basin. Since the UCRB is the primary source of water in the Colorado River Basin, changes in flow of the UCRB are extremely important for the western U.S."

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A stock image shows the Colorado river at Horseshoe Bend, Page, Arizona. Getty